It is well accepted by scientific authorities that living tissue can be made to grow in response to a gentle, sustained tensile force which, in the prior art, has generally been induced through a mechanical arrangement. This phenomenon has been demonstrated in many kinds of living tissues including skin, bone, muscle, nerves, blood vessels, lungs and even in isolated tissue cultures. (See references attached in Exhibit A.) The physiological mechanisms which contribute to this universal property of living tissue have recently been reviewed. (See references attached in Exhibit A.) Furthermore, many useful medical devices have been developed which rely on this universal property of tensile force induced tissue growth. (See references attached in Exhibit A.) However, as mentioned, these prior art devices typically operate through a mechanically induced tensile force occasioned by hooks, pins, or other more invasive, complication prone surgical procedures for establishing mechanical procedures for establishing mechanical connections between which the tensile forces are created.
The inventor herein has himself previously invented a non-invasive, mechanical device for applying a sustained tensile force to a soft tissue or skin surface to thereby enlarge a patient""s soft tissue. The inventor has received patents on these various non-invasive devices and methods including U.S. Pat. Nos. 5,695,445 and 5,662,583, the disclosures of which are incorporated herein by reference. While the inventor""s work is continuing, he has engaged in rigorous clinical testing as a necessary predicate to receiving FDA approval which has confirmed the clinical effectiveness of his devices and methods in enlarging soft tissue including female breasts. More particularly, the device used in his clinical studies utilizes a low level vacuum to apply a tensile force on the skin surface of a breast, with an adhesive surface being used to seal the vacuum against the patient""s skin. This device takes the form of a bra-like appliance which is portable and aesthetically acceptable in that its presence is virtually undetectable as it is worn by the patient during her daily activities. These prototype devices being used are fully operational and have confirmed the effectiveness of a sustained tensile force in achieving soft tissue growth and enlargement.
As the inventor has continued his further work and development in this area, he has continued to seek ways to improve his devices with respect to their effectiveness, aesthetics, and comfort to a potential patient. One of the more difficult problems to solve with the inventor""s vacuum based devices has been the need to maintain the vacuum as the device is worn throughout daily activities and yet be so unobtrusive as to be undetectable to those around the patient and who may be in close proximity to her. The inventor has developed one such device in which a vacuum may be established as the patient begins her day, and then supplemented or even reestablished with a hand operated pump and valve mechanism should the vacuum become reduced to an unacceptable level or otherwise escape as the patient twists and bends her torso in her normal daily activities. However, even with this particular arrangement, the inventor has sought to further improve his device by developing an alternative means for delivering a distracting force and yet permitting the patient to twist and turn her torso as needed without the inconvenience of reestablishing or supplementing the vacuum needed to achieve the soft tissue enlargement. While the inventor had previously conceived of various mechanical arrangements for establishing and maintaining a tensile force in this application, and indeed received U.S. Pat. No. 5,662,583 issued Sep. 2, 1997 for several of them, these arrangements were subject to their own difficulties. For example, several of them required a somewhat elaborate arrangement of mechanical springs, wires, interleaved shell members, or other such mechanical and moving parts as to be fairly intricate and perhaps difficult to reliably implement. Another embodiment disclosed and claimed in the ""583 patent included utilizing an intermediate material which could be caused to shrink upon curing. While such a curably shrinking material could effectively create the desired tensile force, it would necessarily require replacement of the once shrunk intermediate material at least on a daily basis as the patient would remove the bra and then reapply it. For these reasons, among others, the inventor has previously focused his activities on vacuum based devices.
In order to solve the potential difficulties with maintaining a vacuum in the vacuum based devices and the intricacies of the mechanical devices, the inventor herein has succeeded in conceiving and developing a further mechanical embodiment for creating the required tensile force in a soft tissue expander. More particularly, the inventor has conceived of utilizing a xe2x80x9cmemory materialxe2x80x9d which may be moved into a first physical arrangement for being adhered to the surface of the soft tissue desired to be enlarged, and then causing the memory material to transform into its second physical arrangement to thereby create the required tensile force. The first physical arrangement may be a non-memory arrangement and the second physical arrangement may be the memory arrangement. More particularly, the memory material may comprise one of the shape memory alloys, an example of which is Nitinol as disclosed in U.S. Pat. No. 3,174,851, the disclosure of which is incorporated herein by reference. Nitinol and some other related nickel-titanium or copper-zinc-aluminum methyl alloys have a xe2x80x9cshape memory affectxe2x80x9d that has been previously utilized in a number of useful medical devices. These include as an orthodontic arch where the arch is cooled and then placed in the patient""s mouth which warms it and moves it into a stressed shape to exert pressure on the patient""s teeth. Still other medical applications known to the inventor are as an expandable filter which is used in the blood vessels and as a bony anchor. These shape memory alloys or xe2x80x9cSMAxe2x80x9d have two crystalline phase forms with a transition temperature that can be set at approximately normal body surface temperature (approximately 30 degrees centigrade). At temperatures greater than this transition temperature, these alloys prefer the Austenite phase while at lower temperatures they prefer the Martensite phase. The Martensite phase crystal structure consists of a series of planes that may be readily displaced allowing the alloy to be easily deformed in nearly any direction. When the alloys are heated to a temperature at or above the transition temperature, the Austenite crystal phase is preferred which forces the planes to revert back into their original configuration. In effect, this hardens the alloys and forces them to spring back and restore their original or xe2x80x9csetxe2x80x9d shape. These alloys may also be activated by passing an electrical current through them. Thus, these metal alloys give the appearance of xe2x80x9crememberingxe2x80x9d their originally set shape. Cooling and heating these alloys below and above the transition temperature can be repeated thousands of times, each time changing the property of the alloy from being soft for fashioning into a second physical arrangement to rigid which causes them to spring back into their set shape or original physical arrangement. the set shape or xe2x80x9cshape memoryxe2x80x9d may be set by imprinting the desired form or shape into the alloy and then heating it to temperatures approximating 500 degrees centigrade.
In addition to shape memory alloys, certain plastics may also be engineered to move between a first physical arrangement and a second physical arrangement as a function of temperature, as known to those of ordinary skill in the art. These plastics may also be utilized as a xe2x80x9cmemory materialxe2x80x9d suitable for implementing the present invention.
In implementing these memory materials, the cups or domes described in one or more of the inventor""s previous patents could include some form of memory material in their fabric. Below body temperature, these domes would be soft and conformable to the shape and contour of the underlying breast or soft tissue surface to be enlarged. As the patient""s body temperature heats the domes and memory material, they will tend to revert and spring back to their previously imprinted xe2x80x9cmemoryxe2x80x9d of a deeper/wider dome. If appropriately adhered to the underlying soft tissue surface or skin, this reversion or xe2x80x9cspringing backxe2x80x9d of the memory material will then impart a tensile force to the underlying skin or tissue surface as would be effective for creating soft tissue enlargement in a suitable therapeutic regimen. Additionally, a small battery operated electronic circuit may be provided to activate and increase the tension of some of the fibers that would be set for a higher transition temperature. This would allow the bra to operate in an intermittent duty cycle in addition to maintaining a constant tension.
In order to appropriately distribute the tensile force while at the same time adhering the memory material to the underlying tissue, a layer of gel, or an air or other fluid filled bladder, may be an appropriate interface between the skin and layer of memory material, and an appropriate adhesive substance placed between the layer of gel and the underlying skin. As the inventor has disclosed in one or more of his prior patents, this adhesion could be effected with any one of a well known group of surgical adhesives which are known to bond appropriately to a skin surface without damage for extended periods of time. This may preferably be a layer of sticky silicone gel. Alternatively, the inventor has further conceived of implementing the principles of surface tension as a non-abrasive way of achieving this necessary adhesion. More particularly, a fluid may be placed on the gel layer, or on the patient""s soft tissue just prior to application of the bra, and the inventor has found that the forces attributable to surface tension are sufficient to maintain an appropriate adherence between the soft tissue and the gel as the memory material transitions physical arrangement to thereby impart the desired tensile force. Thus, the inventor has conceived of utilizing a memory material for mechanically inducing a tensile force in an appropriately chosen soft tissue site, as well as the concept of utilizing a thin layer of fluid as an interface for creating a surface tension to maintain adherence between a layer of gel or other intermediary layer to insure a distribution of the tensile force across the skin surface to thereby avoid undesired shear forces or other concentrating effects which might cause undesired abrasion or damage to the skin surface.
While some of the principal advantages and features of the invention have been discussed above, a fuller understanding of the invention may be attained by referring to the drawings and description of the preferred embodiment which follow.